If I'm interpreting you right, it wouldn't be easier to automatically lock all threads once they reach two months. I'm not sure there is even a function that would allow us to do that automatically, and there is no point locking a thread automatically only to unlock it if the OP wants it.

You may specify a time period from which to display threads. Threads older than the age you specify will not be shown.
Default Thread Age Cut Off:

One of those options is "forum default." I have a feeling the default is not two months. Perhaps it could be?

Edit...it also appears that setting doesn't quite work. I believe mine is changed to two months and I'm seeing older threads.

Oh. I get what you're referring to now.

And the setting you are referring to and the two month bumping rule are not meant to be linked in any way. Older threads can still be useful, but they can't be posted in, so that's why that option isn't used automatically.

As Endeavour said, these threads are beneficial for some users, and those old threads are often what like.. they attract people to VT. Those are the threads that get archived with search engines and appear up when people google, more so than the new threads, and we do want them to be visible for all to see.